This invention relates to a novel antifouling paint composition.
Antifouling paints containing as a vehicle resin a trialkyltin group-containing polymer are known as "self-polishing antifouling paints". When these paints are applied onto ships as a coating film, the film is gradually hydrolyzed by the action of weakly alkaline sea water to release the trialkyltin moiety at a constant rate for a long period of time, and at the same time the remaining film may be rendered water-soluble to expose a fresh surface of the tin-containing polymer. This smoothens the film surface consistently, decreases the frictional resistance of the ships and, therefore, economizes fuel consumption.
The tin-containing polymers used in the known self-polishing antifouling paints consist typically of copolymers of trialkyltin acrylate or methacrylate with other ethylenically unsaturated monomers.
However, ecological concern of massive release of organotin compounds into sea water makes the tin-based antifouling paints undesirable and a need arises for a new vehicle resin usable in the self-polishing antifouling paints.
In Japanese Patent Kokai No. 16809/1989 published on Jan. 20, 1989 and assigned to the assignee of the present application, a metal-containing polymer is disclosed comprising a multivalent, metal salt of acrylic or methacrylic acid copolymers with a monobasic organic acid bound to the same metal ion to which the acrylate or mathacrylate anion is bound.
It has been found, however, that this type of metal-containing polymers are liable to ion-association and tend to react with antifouling agents such as cuprous oxide or copper rhodanide or metal oxide pigments such as zinc oxide when formulated them together in an antifouling paint. Consequently, the paint formulations will become gelled or too viscous upon storage making them commercially impractical.
Accordingly, it is a major object of this invention to provide a self-polishing antifouling paint of the above type which is free from these problems and is compatible with conventional antifouling agents or conventional metal oxide pigments.